AMMAN, Jordan — Hard-pressed by a tightening trade embargo, the government of Iraq retaliated Wednesday by beginning to take over foreign assets in Iraq and withholding payment on its debts.

In decreeing the move, Iraq's ruling Revolutionary Command Council targeted countries that have frozen Iraqi and Kuwaiti assets abroad and have deprived Iraq of the proceeds of Kuwait's vast investments.

The official Iraqi News Agency, which made the decree public, said it was issued under a new law dealing with the protection of "Iraqi interests, money and rights in Iraq and abroad." It quoted the decree as saying:

"All money, assets and their revenues belonging to governments, institutions, companies and banks of countries that have taken arbitrary actions against Iraq are impounded."

The news agency did not say how much money might be involved, nor was the U.S. State Department able to provide an estimate. Margaret Tutwiler, a department spokeswoman, said in Washington:

"It is not clear from the Iraqi statement in what form or against whom the action will be taken."

The United States, and other countries as well, froze Iraq's holdings abroad not long after Iraq invaded and occupied Kuwait on Aug. 2. According to the Iraqi News Agency, the new decree declares that action invalid.

Iraq's order to seize foreign assets is the latest in a series of tit-for-tat moves President Saddam Hussein has made in an effort to counter the foreign pressure. Inresponse to the trade embargo, he has withheld food from foreign refugees trying to get out of the country; in an effort to deter military attack, he has moved foreign hostages to potential target areas.

The decree's impact will vary from country to country. Britain, for example, has little in the way of assets in Iraq and is a net debtor. Several Japanese companies, on the other hand, are owed about $4.5 billion by Iraq.

Several foreign companies have lucrative construction and oil contracts with the Iraqi government, and Iraq has taken the position that it will not be responsible for delays in completing these contracts, suggesting that it will not pay for incomplete projects.

There was speculation in Amman that Iraq will confiscate diplomatic property in Kuwait. Hussein has already ordered embassies there closed and suspended guarantees of diplomatic safety.